Resin bonded abrasives



Patented May 1946 slums:

PArsN nssm nonnnn snnnsr'vns 3 In, Brookfleld, Mnss.,assignor to Lorin:

' Norton Company. Worcester, corporation of No Original application 20, 1943, 861181, N- 479,903. llldjhll p 'plication June 26 1943 Serial N0. 92,115

new. (c1. Iiisms 'l'his invention relates to grinding wheels" and other solid abrasive compositions and relates also to resins and resinous compositions of the phenol formaldehyde type; more particularly, this invention relates to abrasive articles'og the kind Just mentioned thatare bonded with organic or resin bonds, especially the p lymerized condensation product of phenol with an aldehyde, and also to resin of the Just-mentioned kind an their. compositions andtreatment, This application is a division of my application, Serial No. 479,903 filed March 20, 1943.

' One of the objects of this invention is to provide a superior plasticizer for. abrasive grains for the manufacture of abrasive compositions of the above-mentioned type and, more particularly, to improve the characteristics, both during processing and in the flnalabrasive product, of resins of the Just-mentioned kind. Another object isto facilitate, expedite and simplify the making of abrasive articles utilizing resins of the aboveas heretofore known and used. Another object is to provide a method of treatment and curing of phenol aldehyde resin that will for practical purposes avoid the formation of water or water vapor q and detrimental actions caused thereby such as blistering, bloating, swelling or the like. Another object is to provide a plasticizing and hardening 1 agent forphenol aldehyde that will not arrangements of parts, and in. the several steps and relation and order of each ofsaid steps to one or more of the others thereof, all as will be illustratively described herein, and the scope of the application of'which will be indicated in the. following claims.

Grinding wheel and other abrasive products have heretofore been made by using phenol aldehyde resins together with a plasticizer or hardening agent, usually furfural, usually bymaking amix .of these ingredients and of abrasive grain,

thus forming what is knownas a dry granular mix. then cold-pressing and heat-treating in an oven, or. by so-called hot-pressing in which the or other abrasive body, utilizing phenol aldehyde resin as a bond, that will not, during the process of compounding and treatment for making it, react to form water 1 and thus cause blistering, bloating or the like. Another object is to provide a method and treatment for effecting, without the detrimental formation of water, dependable bonding by phenol formaldehyde resin of abrasive grains to produce abrasive wheels or other abrasive articles. Another object is to provide a mixing plasticizer and hardening agent ing abrasive grains and such resin for the making of grinding wheels and other abrasive articles.

Another object is to improve the working and curing characteristics of phenol aldehyde resins dry mix is molded and pressed in a heated mold and cured; in either case, molds ar required for the various shapes and sizes of product to be made, these molds are usually constructed for use in hydraulic presses or the like, and hence involve substantial and expensive equipment, and in the hot-pressing method costly equipment like hydraulic presses is tied up for substantial lengths of time. Generally similar disadvantages ar present in certain heretofore'known or now practiced methods of molding objects or articles 7 out of phenol aldehyde resins, usually with some for the phenol aldehyde resin of'mixes comprissort of filler or fillers; or without a filler. One

reason why such disadvantages are presentin v such and other methods of molding products utiand to avoid certain shortcomngs of such resin fural, commencesa substantially immediate reaction with the resin which is usually employed in powdered form so that the mix undergoes-what might be termed a preliminary setting though il equiring an ultimate heat treatment to ef-' fect final curing; as a result of this preliminary setting, variou limitations are necessarily imposed upon the handling or processing and the field of application of such resins substantially correspondingly restricted. One of the dominant aims of this invention is to overcome such disadvantages and limitations and to enlarge the, field of use of such phenol resins.

The practicing of my invention, in its various aspects and also to give certain specific illustrations of certain of its advantages, will be understood by considering the making of an abrasive composition, such as a grinding wheel. Accordingly, I start with a suitable quantity of abrasive grain of any .suitable kind; Thus I may employ any of the varieties of alumina, such as emery,

corundum', dense regular" fused alumina, po-

rous white fused alumina; silicon carbide and other hard carbides: quartz; glass; garnet; or

diamonds. These are illustrations and,- of course,

two or'more of these abrasives may be mixed, if desired. Such abrasive grain is to be bonded to form, for example, a grinding wheel.

If, now, I- were to employ a phenolic resinaccording to known practices, using, for example,

, furfural as a grain-wetting and resin plasticizing or hardening agent, the resultant so-called granular mix begins to set and has to be reasonably promptly molded and cured, as by hot-pressing as above noted or as by cold-pressing as above described, requiring relatively costly equipment and frequently tying such equipment up for substantial lengths of time; such a mix, moreover, cannot be worked on mill rolls, because it is too sticky and because hardening or setting commences or proceeds, Also, because of such disad vantageous characteristics, phenolic resins or mixes,-usually with some sort of illler,'whe n em.- ployed for the making of products other than abrasive articles, impose limitations upon themanner of handling them in the uncured state:

for example, being sticky and subject to progressive hardening when in the plastic or doughy state, they do not lend themselves for so-called injection molding. 4

However, according to my invention, I am enabled to overcome such disadvantages and in effect enlarge the field of uses or applications of am nes.

taeh itself, to form an adequately cross-linked polymer which is a hardened, tough resin body.

With such a hardening agent and with a phenolic 'ment of the advantages and benefits of my invention.

There is a goodly ;number of ways in which --I can aminate a phenolic resin, thus to make available anamino group or nitrogen atom for subsequent cross-linking with a hardening agent of the above-mentioned kind. For example, I

may react phenol and-formaldehyde and ammonia (NHa), and the resultant potentially reactive resin would be suitable to function according to my invention; the ultimate or end product can be made to be fusible or permanently infusible according, as is known, to the proportion of phenol and formaldehyde initially employed. In such a condensation reaction, the ammonia acts primarily as a catalyst but it also acts as an aminating agent, bringing into the resin molecule polymer an amino or nitrogen atom group. A preferred manner of providing the nitrogen atoms for ultimate cross-linkingor co-polymerization with a hardening agent of the above-mentioned character to form a hard resinous body is to employ, in powdered form, an admixture of potentially reactivephenolic resin, such as phenol formaldehyde, and hexamethylenetetramine, hereinafter referred to simply as hexa;

phenolic resins or simplify and make less expen- .sive their uses in certain fields, or both. I have discovered how to avoid the above-mentioned undesirable stickiness and progressive hardening and how to make up an uncured plastic phenolic resin mix that does not havedetrimental tackiness or stickiness and that is capable of retaining the desirable quality of plasticity or flowability and thus permit use of quite different and more advantageous methods of working. molding, shaping or the like, for subsequent heat treatment or subsequent curing.

My invention is applicable to the phenol aldehyde resins and, for purposes of illustration. I will describeit in connection with phenol formaldehyde resin.

In carrying out my invention and as I now understand it, I 1 make available, for cross-linking during polymerization under subsequent heat treatment, nitrogen atoms in the resin polymer molecule and to which the plasticizing or hardening agent, of a kind heretofore not employed in connection with phenolic resins, can link or. at- '15 Or I may react phenol and formaldehyde in such an admixture is sometimes regarded as a solid solution of the hexa in the resin and is, moreover, available on the market under the designation Bakelite BR 2417," a, product of Bakelite Corporation. In producing such potentially reactive resin, the hexa is mixed with the phenol formaldehyde, the mixture is melted and, after cooling, the resultant solidified mass is broken up and powdered for use. .In such powdered form, the hexa is in solution in the resin and is available for aminating the resin during subsequent heat-treatment during which, also, the

hardening agent employed according to my process cross-links with the aminated resin at the nitrogen groups thereof.

0r, depending, for example, upon the characteristics desired in the end product, I may react phenol and formaldehyde and ammonia in .the manner above described and to the resultant potentially reactive resin, preferably in powdered form, I add a suitable quantity of hexa; also in powdered form; the former is aminated during the condensation or reaction in the presence of ammonia fand the latter can function as an aminating agent during .the subsequent heat treatment of the resultant mix in admixture with the hardening agent.

Amination of the phenolic resin may also be effected by adding a suitable quantity of aniline to the phenol and then reacting with formaldehyde in the presence of a catalyst which may be 'sodiumhydroxide, calcium hydroxide, or, by way 01' further example, ammonia.

mo preaenooor an aliphatic amine m tageous' selection is available.

the'first above-described illus trati'onfland any suitable aliphatic amine may i be employed, such as methyl amine, ethyl amine,

propyl amine, etc.

Amination of the resinmay thus be effectedprior to or during'iinal' heat-treatment or, in

point oftime, the one may supplement the other, as inthe case of the third above-described exam'ple;- unless otherwise qualiiied, therefore, the-terms amina or aminating" or faminated" as' used in'the claims are intended tobegeneric and'without regardrto the specific Place of: a

' amines time, stage, or ;stepin which amiiiation of the resin polymer molecule takes'place, 1 a

I Iii-making up an abrasive product, the de sired quantity of abrasivegrainanda suitable 1 quantity of the resin'in powdered form-,such as the above mentioned phenolic-resin, such -as, I

phenol formaldehyde resin, treated with hexa, for example, the above-mentioned BR' 2417, and ,a' plasticizer "and hardening agent, preferably in liquidformg of a kind capable of attachment mixed together suitable way; 'As an illustration of' such ja plasticizing and harden: .ingagent,;1 may employ tri-glycol dichloride; numerous othersare;.mentioned later hereinafter. I-have found that a wide and advan- .For example, I 'r'nay treat the liquid harden ing agent'as a grain-wetting agent, thus first wetting the surfaces of the grains, and then adding the powderedresin, the pre-vniating of to or cross-linking; at the nitrogenatoms'oi the resin polymer; molecule,-and with or'without other substances,"such-as flllersor the like, are

the grains insuring int'the ensuing mixing oper-.

.ation thatthe particles ofthe powdered resin" adhere to and cover over the .surfaces of the grains. In this manner, with other ingredients added and intermixed'therewith, such .as fillers, l

dehydrating agents, dehalogenating agents or the like, as may, be desired, a so-called 'dry' granular mix results. This mix is free from the above-mentioned detrimental rate of hardening thesheet itself. Thus cut out et the sheet, the

V 3 and; hence where-the material contains abrasive: grain, are cut out of the-sheet, the disks retaining, of course, the thickness of articles can be easilyhandled and may then be i heat-treated in an oven, in large quantities,

care-being taken that each article when put in the oven rests upon a suitable flat surface to avoid distortion and to avoidcuringit indis torted" form. Particularly when .makingrelatively thin grinding wheels, this method of working up on mill rolls, ealendering into sheet-form and cutting outof the disks has numerous advantages of which .it is suflicient to note the simplicity. and inexpensiveness of equipment needed,.the avoidanceof tying up of; expensive equipment such asthe presses' in the fhot-presse a method, and the possibility ofcuring continuously or in large groups simultaneously of numerous articles or products.

Moreover, I am enabled to achievenumerous other advantages. For example, it is not'necessary, though it may be 'desirableor preferred according to circumstances, first to ,wet the abrasive grains; thus them may be made up initially without the abrasive grains, for example, by mixing the powdered resin with the liquid plasticizer: or; hardening agent, in, any. suitable .mixer. The resultant dough-like or plastic masscan then be transferred to mill rolls further to work it up or to complete the mixing ofits ingredients, and while working it on the mill rolls: other ingredients such as those mentioned above,- and even also theabrasive rain (which can be in dry condition) can be added and worked intothe mass. Pro-wetting of the grain, in the case-of making abrasive I varticles; need not be resorted to since, in adding the grain to the mass while it is being workedup onthemill rolls, the-latter and the resultant working up of the massinsure that there is such complete and uniform distribution-of the grain throughout the, mass and" engagement of the at room or working temperatures, and it maybe shaped or molded in any desired way without havingtohave regard for progressive hardening, and it may subsequently be heat-treated in ing it through the millrolls to effect or complete the mixing, thereof and during working up on such mill rolls other ingredients, such as grain surfaces with the material of the mass as will, in the end-result or end product, produce uniform and good bonding together of the grain.

When sheeting out the plastic mass, as by the above-mentioned calenderrolls, and thereafter cutting 'out the desired configuration of articles, such as disks for grinding wheelsor othershapes of abrasive body, or any other desired shape or conflgurationwhen the mass does not include abrasive grain, a certain amount of the sheeted material is left over, as, forexample. the regions intermediate of adjacent or successive disks when cutting out grinding wheels, but here it is, to be noted that such left-over material is not scrap or wasternaterial, but, because it is not undergoing progressive hardening. to any detrimental extent, the left-overmaterial, even though in pieces of various sizes, can simply be gathered.

I togetherl and fed to the mill rolls to be by them I fillers, etc., may be added progressively or in any desired manner and thereafter, depending upon-the-ultimate product, the plastic mass may be sheeted out in calendar'rolls to the desired thickness and with the desired compactness.

Insofar as I am aware, it has heretofore been impossible to so treat a phenolic resin mix,

whether or not it contained abrasive grain, the

' stickiness and progressive hardening noted above precluding such treatment.

When'sheeted out, the desired configuration of ultimate article desired is cutout of the sheet and in the case of making grinding wheels 75 phenolic resin mixes, otherwise precluding workworked up into a unitary mass, which continues its plasticity or quality of flowability. It may then again be calendered to sheet it out and thus again to have articles cut out of it for subsequent baking or curing. Left-over material may again be reworked or added to anew batch or mix on the mill -rolls. Thus wastage as would result if the phenolic resin mix underwent progressive hardening, as with heretofore known phenolic resin compositions, can be'avoided, evenlassuming thatthe stickiness or tackiness of such prior ing on mill rolls and calender rolls, could be eliminated or avoided.

Moreover, also, the potentially reactive phenolic resin mixof my invention, particularly in the making of non-abrasive resinous articles, lends itself to so-called injection molding because, not being detrlmentally sticky and retainemployed, the resultantproduct is fusible under,

the application of heat, or is a thermo-irreversible body, as will now be clear in view of the above. Thus it will be seen that the production of phenolic resin products can be more emciently and less expensively eflected; for example, heat treatment or curing in the mold, requiring a time element, can be eliminated, molding apparatus can be simpler and less expensive in that the features of heating need not be employed, and the tying up of expensive equipment, such as is used in heat and pressure molding. can be avoided.

As pointed out hereinafter, -I am enabled furthermore to achieve other advantages.

Considering more in--detai1 the reactions that take place, let it again be'considered that the above-described phenolic formaldehyde resin with hexa and tri-glycol dichloride are employed. The presence of the nitrogen atom in the potentially reactive phenol formaldehyde resin is due to the fact that the reaction of the resin (phenol formaldehyde in the above-assumed illustration) and the hexa produces some groups of the following type, hereinafter called, for convenience, Group A:

Group A' In the above, note the NH or nitrogen atom group, available for cross-linking. 1

Tri glycol dichloride is written thus;

cii-c-o-e-e-o-i- -cl i t i t at I formaldehyde resin polymer alkylated by the hexa so that ,a-nitrogen atom is introduced into of the following type:

a n g o lai i i lee.

It will be noted that the plasticizing or hardening agent cross-links with A" groups at the amino groups of the latter, specifically "at the- NH or N atom groups, and without the provision of the latter, the tri-glycol dichloride would not function as it does as a plasticizing or hardening agent. It will thus be noted that the phenol formaldehyde resin, in being thus provided with a nitrogen atom or atoms in its continuous chain cross-linking with the tri-glycol dichloride and that such preparation can be effected as well as final cross-linking with the trl-glycol dichloride, not only without detracting from the ultimate desirable qualities of the hardened resin, but also with the achievement of new characteristics, such as absence of detrimental stickiness, maintenance of plasticity or flowability before final heat treatment, and the like.

Moreover, it will also be noted that the triglycol dichloride has functioned as a halogenating agent, H and Cl appearing in the groups of the cross-linked polymer at the amino groups thereof. This is advantageous when making abrasive products, such as grinding wheels, for the heat generated at the grinding line causes the release from the structure of hydrogen chlo-' ride, thus coacting to achieve improved or bet ter grinding action.

Numerous other substances may be employed, besides tri-glycol dichloride. Thus. I may use dichlor diethyl ether;- other poly-glycol dichlorides may also be used, for example, tetra-glycol dichloride, or penta-polyglycol dichloride, and of course, mixtures of two or more may also be employed. Compounds of large molecular weight, that is, having additional cam groups, are solids and, without more, cannot take part in making up a plastic or flowable mass and hence I prefer not to use them. i a

Other cross-linking agents that may be employed, and there are many, include di-monochloracetates of ethylene glycol, poly-ethylene glycol, substituted poly-ethylene glycols and tris OrImayuse -is: V

I 2,401,1ss mcthylene'glycol: di-monochloracetate oi 'ethyl cne glycol is:

' cm-ooc-cmol m-ooc-omci ing phenolic resin, containing the above-mentioned groups "A," again takes place at the nitrogen atoms or the resin polymer molecule and again halogenation takes place in that H and 01 appear in the groups of the cross-linked polymer Cross-linking with the nitrogen-atom containat the amino groups thereof, in substantially the iollowing way which illustrates. with respect to di-monochloracetate of ethylene glycol how the other above-mentioned agents also cross-link;

H 01 I Questi g, I onr co I "I'he just-mentioned substances might all be called glycol di-monochloracetates and of the latter, I prefer to use a y glycol di-monochloracetate selected from the group consisting of ethylene glycol di-monochloracetate, di-ethylene glycol di-monochloracetate, tri-ethylene glycol di-monochloracetate, and tri-methylene, glycol di-monochloracetate.

Still other substances usuable in the above manner may comprise tri-monochloracetates oi certain trihydric alcohols, more: particularly in the use of glycerol tri-monochloracetate or trimethylol propanetri-monochloracetate, or mixtures thereof. Glycerol tri-monochloracetate is written thus:

cm-ooc-cm-ci H-OOC-CHr-Ol m-ooc-cm-cx The latter may he used to illustrate the, crosslinking of ingredients oi. the above-mentioned group, substantially as follows:

'- 'n ci onOcm N-cm-C -0n I I I I v EHs-OOb-LH:

n-ooc-cmci m-ooc-cm cnr lL-cn on Q 11 m g Also, I may use esters of ethylene chlorhydrins with polybasic acid; thus, I may use, di-2chlorethyl phthalate; this ester is: I I

C 00-CHr-CHz-Cl COO-CHrClia-Cl Or I may use di-2chlorethyl succinate; this ester di-2chlorethyl maleate: this ester cm-ooo-cnr-ci m-ooo-om-ox I The cross-linking may be set out substantially as follows: a

. n 01 (so 3.: e800]; in. (mm) cm. on,

(Mslesto) CaHi (Sucoinste) GzH (5H:

Other usable esters comprise chloracetates of glycerol chlor-hydrins or'mixtures thereof and conveniently a mixture is employed: for example, I may start with glycerol a7 dichlorhydrin and glycerol up dichlor-hydrin, which are, respectively, or may be written thus:

om-cl OHr-Cl inen and 11-01 iii-o1 Hr-OH Mixtures of the above form chloracetates when" reacted with chloracetic acid; such chloracetates are, respectively, or may be written thus:

CHg-Cl OKs-Cl .H-OO G-CHiCl and HCl H:Cl Hr-O O C-CHsCl Cross-linking of the mixture with the nitrogenbearing phenol formaldehyde resin is substantially like this:

I v n 01 I OH CHr- -01! on Thus it will be seenthat there are numerous compositions that can be employed; these agents the end product and this is of advantage in the makin of abrasive articles in that the grinding action, due to the release, in the above illustrations, of hydrogen chloride, is improved. In each case, the H and Cl appears attached at tht nitrogen atom group.- Naturally enough, the examples above set forth are chlorinated compounds because these are cheaper and more readily available or producible than other halogen- 6 ated compounds, such as the bromine-ted or iodated, but halogenated compounds other than.

the chlorinated will give eflectiveresultsand the setting forth of suchchlorinated compounds'as the above is not to be interpreted by way of limitation.

Examples of the compounding, treatment or method of making resinous products according to my inventionv are set forth below, illustratively in connection with the making of grinding wheels, and in the latter particularly numerous practical advantages are achieved; the following examples are set forth with respect to only a few of the above-mentioned usable agents.

Example I 550 grams of No. 46 grit "Klundum abrasive" grain and 230 grams of a mixture comprising, by volume 65% of BR 2417 resin, 30% of iron pyrite, and of calcium oxide, all in powdered form. are mixed together with 20 cc. of tri-glycol dichloride. As will be clear from what is'set forth above, there is wide flexibility in the. manner in which these substances are brought together. Thus the grain can first be wet with the tri-glycol dichloride and, then the mixture added thereto. and all preliminarily mixed in any'suitable form of mixer, to form a plastic mass which may then be worked on differential mill rolls and then sheeted out as by calender rolls. Or the above mixture of hexa resin, iron pyrite and calcium oxide may be mixed with the tri-glycol dichloride, as in a suitable mixer, to form a plastic mass to which the abrasive grain may thereafter be added as, for-example. while working the i Trample]? 2,000 of No.40 grit-Alundum abrasive grain was wet with 100 cc. of di-ethylene glycol chloracetate and then there was added 800 grams of a mixture consisting, by volume, of 65% of phenol 1 formaldehyde resin containing 8%, by

like mass which was then rolled down in calender rolls to a thickness of of an inch, whereupon a disk of 12" diameter with a 1" central hole was" cut from the sheet, giving a green wheel.

The green wheel was put on a batt and so supported was baked in an oven at suitable temperature and, in this instance, was baked for 3 hours at 100 0.; then '3 hours at 125 0., then 3 hours at 155 (1., followed ,by 4 hours at 175 C.

The finished wheel was then tested in wet and drygrinding on a cut ofl machine, operating upon 5 inch cold rolled steel rod, running at 10,500 8. F. P. M. The average diametrical wheel wear,

per cut, for 80 dry cuts was 4.8 mils.

plastic mass up on the mill rolls, thus to thoroughly distribute the grain throughout the mass as well as to complete the mixing oi" the other ingredi'ents thereof, and then sheeting out in calender rolls. These are but two illustrations of available flexibility of procedure at this stage; a similar flexibility, it will be understood, is avail able with respect to the other examples set out hereinafter.

In a specific illustration, this plastic mass which, it will be seen, could also be in the form of a granular mix where th mix is first made up with abrasive grain, as in a rotary "Hudsonf type of mixer, was worked on mixing rolls, such as differential mill rolls, with the rolls cold or at or about room temperature, and on such rolls the resultant sheet-like mass, still plastic, was

rolled down in calender rolls to the desired thickness, in this illustration it of an inch. From the resultant sheet a disk of 12 inches in diameter with a 1 inch hole was cut, that being the form, shape and-dimensions desired in the final product, and it may in this instance be termed a,

Thesresultant grinding wheel had a porosity of 7% and was abrasive by volume. Its grinding performance was good; it was tested at 10,500 surface feet per minute upon Y2 inch cold rolled steel rod and showed a die-metrical wheel wear of 6.7 mils per cut.

v Example HZ 2,000 grams of No. 46 grit "Alundum" abrasive grain was wet with 100 cc. of glycerol chlorhydrin chloracetate and then there was added 800' grams of a mixture consisting, by volume, of of phenol formaldehyde resin containing 8%, by

weight, of hexa (being in effect 332M? resin),

30% of iron pyrite and 5% of anhydrous calcium sulphate, all in powdered form. Mixing was carried on in a rotary Hudson type of mixer until a so-called dry granular mix resulted.

The dry granular mix or mass was then worked on cold differentialmixing rolls into a solid sheetlike mass which was then rolled'down in calender -rolls to athickness of a, of an inch, whereupon a. disk of 12" diameter with a 1" central hole was cut from the sheet, giving a green wheel.

The green wheel was put on a batt and'so supported was baked in an oven at suitable temperature and, in this instance, was baked for 3 hours at-" C., then 3 hours at C, then 3 hours at 0., followed by 4 hours at C. The finished wheel was then tested in wet and dry grinding on a cut-off machine, operating upon A inch cold rolled steelrod, running at 10,500 8. F. P. M. The average diametrical wheel wear, per cut, for 80 dry cuts was 6.0 mils.

Example IV 2,000 grams of No. 46 grit "Alundum abrasive grain was wet with 100 cc. of dlchlor ethyl phthalate and then there was added 800 grams of a mixture consisting, by'volume, of 65%. of phenol formaldehyde resin containing 8%, by weight, of hexa (being in eilect BR. 2417 resin), 30% of iron pyrite and 5% of anhydrous calcium sulphate, all in powdered form. Mixing was carried on in a rotary Hudson type of mixer until a socalled dry granular mix resulted.

The dry granular mix or mass was then worked on cold differential mixing rolls into a solid sheet-like mass which was then rolled down in calender rolls to a thickness of a, of an inch, whereupon a disk of 12" diameter with a 1" central hole was cut from I the sheet, giving a reen wheel.

The green wheel was put on a batt and so sup- .ing of my invention.

ported was baked in an oven'at suitable temperature and, in. this instance, was baked for 3 hours at 100 C., then 3 hours at 125 C., then 3 hours at 155 0., followed by 4 hours at 175 C.

The finished wheel was then tested in wet and dry grinding on a cut-off machine, operating upon V inch cold rolled steel rod, running at 10,500 S. F. P. M. ;The average diametrical wheel wear, per cut, for 80 dry cuts was 6.3 mils.

In all of the above illustrations, I have described my invention in connection with phenol formaldehyde, but I do not thereby intend to limit my invention to that particular type of phenolic resins; thus I may use, and my invention isv equally applicable to, such other phenol alde'- hyde resins, such as phenol furiural, cresol formaldehyde, and cresol furfural, as react, in a man- 'ner substantially the .same as is above set forth with respect to phenol formaldehyde which has been selected for illustrativepurposes, in the processing above described, and the term "phe- Just been pointed out can be avoided, and it is also possible to avoid having to resort to expedients of dehydration. Gas formation or evolution during curing has also given troubles or difllculties according to prior compounding, treatment and curing of phenolic resins but in practicing my invention Ihave found no material or harmful gas eifects even though it is possible that 1 small quantities of NH: can be formed due to the vided in this invention phenolic resinous compo- I sitions and a method of achieving them and abranolic resin as used in the claims is intended to include not only phenol formaldehyde but also its equivalents, such as the just mentioned other phenol aldehyde resins. I

I have in the above also pointed out how the hardening agents I employfunction also as halogenating agents and ,how, in the specific illustrations set forth, they react with the nitrogenatom containing phenolic resins to provide H and Cl that-is releasable, during the action and heat of grinding, as hydrogen chloride to improve the grinding action. I might note at this point that, where and if desired, compounds or compositions may be added -to such mixes as those above described in order also or 'further to halogenate the cross-linked resin polymer and among such additional halogenating agents that may be em- --ployed I may use anyof polyvinyl chloride, polydichloride, 'rubber hydrochloride,

vinylidene ticles bonded by a bond that comprises the sub- ,stantially water-free and substantially unswelled chlorinated rubber', chlorinated polyisobutylene;

ailine, hydrocrabon,. such' as hexa chlor ethane,

ene bromide, partly chlorinated eicosane, or any aliphatic halohydrin' of. notmore than six carbonatoms, such as'any of the amylenechlorhydrins;

propylene chlorhydrin; any of the butylene chlorhydrins; ethylene chlorhydrih, ethylene bromhy-. min, or glycerol alpha gamma dichlorhydrin. The Just-named examples happen to be chlorinated compounds because these are cheaper and morereadily producible or available than other such halogenated organic compounds, such as the brominated or iodated compounds, which giveef fective results in bringing or making available at the grinding line acids corresponding to hydrogen polymer at the amino groups thereof, said halide chloride; it will be understood, however, that the use ofsuch additional halogenated organic compounds is not a necessary part or step in my invention and .is hence optional, and is set forth be gained without impairment of the function- Numerous advantages of my invention have been pointed out above, but there are others. For example, phenolic resins as heretofore compounded, treated or cured, are accompanied by -'to show that, if desired, their advantages may the. formation of water, causing disadvantages or diflicultiessuch as bloating or swelling, caused probably also by water .vapor pressures created internally of-the curing mass. But when compounded, treated-or cured according to my insive. articles and a method of making them in s which the various objects hereinbefore noted'together with many thoroughly practical advantages are successfully achieved. Though Iv have set forth in the foregoing specific illustrations pertaining to the making of abrasive articles,the

practicing of my invention with respect to the phenolic resins per se will also be now clear and fully understood. V

As many possible embodiments may be,

varied in various parts all without departing from the scope of the invention, it is to be understood that all matter hereinabove set forth is to be- 30- interpreted as illustrative and not in a limi Iclaim:

1. An abrasive article comprising abrasive parreaction product of an aminated phenolic resin and a resin-hardening resin-solvent agent that is a halide and therefore capable of reaction with the resin polymer at the amino groups thereof, said halide agent bein in said reaction product, cross-linked, with the resin polymer molecules at the amino groups thereof. v

2. An abrasive article comprising abraslveparticles bonded by a bond that comprises the heatcured substantially water-free and substantially unswelled reaction product of potentially reactive phenolic resin, an aminating agent therefor for reaction therewith to provide amino groups in the polymer molecules'of the resin, and a resinhardening resin-solvent agent that is a halide and therefore capable of reaction with the resin capable of reaction with the resin polymer at'the amino groups thereof, said halide agent being, in said reaction product, cross-linked with the phenolic polymer molecules at the amino groups.

thereof whereby production of H20 along with, or as part of, said reaction product is substantially prevented.

4. An abrasive article comprising abrasive particles bonded by a bond that comprises the substantially water-free and substantially unswelled reaction product of initially aminated phenolic resin, an aminating agent for reaction therewith to provide amino groups in the polymer molecules of the resin, and a cross-linking resin-hardening made of themechanical features of the above .inven .tionand as the art herein described might be stantiallyiwaterefree halogenated reaction prodnot. of an aminated phenolic resin and a crossresin-hardeningresin-solvent agent that has the characteristic ofreacting with the resin polymer "at the amino groups thereof and without detrimentalproduction of water of formation and V V am;

. resin-solvent agent thatis a halide and therefore 1 capable of reaction with polymer at the groups thereof, said-halide agent being, in said reaction product, crow-linked with'theresinpolymer molecules at the amino gro p thereof. 5 An abrasive article-comprising abrasive particles bonded by a bond that comprises the sub- Isa perature, injecting the non-tacky and non-coldsetting plastic mix in a separable closed mold shaped to cohform to the'shape of the desired abrasive article, removing-the shaped mass from the mold, and then heat-treating it to eifect hardening.

11. The steps. in the method of making an abrasive article which comprise making substantially non-cold-setting a potentially reactive resin bond mix and abrasive particles by utilizing therein aminated potentially reactive phenolic resin, abrasive particles, and a cross-linking resin hardening resin-solvent agent therefor that being, in said reaction product. cross-linked with 5 the resin polymer molecules at the-amino groups thereof.

' 6., An abrasive article comprising abrasive particles bonded bya bond that comprises the reaction product of a mix that includes an aminated phenolic resin, 9, halide, and a resin-hardening resin-solvent agent that has the characteristic of reacting with the resin polymer at the amino is a halide and hence capable of substantial crosslinking with the aminated resin polymer molecules at the aminov groups thereof only under heat treatment at temperatures substantially in groups thereofand without detrimental production of water of formation and being, in said reaction product, cross-linked with the aminated phenolic resin polymer molecules at the amino groups thereof.

7. An unswelied abrasive article comprising abrasive particles bonded by a bond that comprises the reaction product of an aminated phenolic resin and a cross-linking halide resin-hardening resin-solvent agent cross-linked with the resin polymer molecules at the amino groups thereof.

8. The steps in the method ofmaking an abrasive article which comprise in substantially non-cold-setting a potentially reactive resin bond mix and abrasive particles by utilizing therein aminated potentially reactive phenolic resin, ab-

rasive particles, and a cross-linking resin-hardening resin-solvent agent therefor that is a halide and hence capable of substantial cross-linking,

with the aminated resin polymer molecules at the amino groups thereof only under heat treatment at temperatures substantially in excess of excess of room temperature, sheeting out the abrasiveresultant non-cold-setting mix to the desired thickness and shape. and heat-treating peratures substantially in excess of room temperature, working the non-tacky and non-coldsetting abrasive mix onmill rolls and sheeting it out to the desired thickness, cutting out of the resultant sheet form the desired configuration room temperature, shaping the resultant noncold-setting mix' and heat-treating it to effect 'cross-linmng and hardening.

9. The steps in the method of making an abrasive article which comprise 'making substantially non-coid-setting a potentially reactive resin bond mix and abrasive particles by utilizing therein aminated potentially reactive phenolic resin, ab-

' rasive particles, and a cross-linkingresin-hardening resin-solvent agent therefor that is a halide and hence capable of substantial cross-linking,

with the aminated resin polymer molecules at the amino groups thereof only under heat treatment at temperatures substantially in excess of room temperature, cold-molding the resultant noncold-.-setting mix to give it the shape of the desired abrasive article, and then heat-treating the shaped mix to effect cross-linking and hardening.

10. The steps in the method of making an abrasive article which comprise making substantially non-cold-setting and substantially non-tacky a potentially reactive resin bond mix and abrasive particles by utilizingtherein aminated potentially reactivephenolic resin, abrasive particles, and a cross-linking resin-hardening resin solvent nated resin polymer molecules at the amino groups thereof only under heat treatment at temperatures substantially inexcess of roomtemof abrasive article, and heat-treating the cut-out configuration to effect hardening.

13. The steps in the method of making an abrasive article which comprise making substantially non-cold-setting and substantially nontacky a potentially reactive resin bond mix and abrasive particles by utilizing therein aminated potentially reactive phenolic resin and a crosslinking resin-hardening resin-solvent agent therefor that is a halide and hence capable of substantially cross-linking with the aminated resin polymer molecules at the amino groups thereof only under heat treatment at temperatures substantially in excess of room temperature, working the substantially non-tacky and non-cold-setting mix on mill rolls and: adding thereto, during the working, abrasive grain, calendering the resultant abrasive mix out into substantially sheet form, cutting out of the sheet form the desired configuration of abrasive article, and heat-treating the cut-out configuration to effect hardening.

' 14. The steps in the method of avoiding swelling due to water of reaction formed during the making an abrasive article utilizing phenolic resin as a bond ingredient, which comprise making up a potentially reactive mix that comprises aminated potentially'reactive phenolic resinand a cross-linking resin-hardening resin-solvent agent therefor that is a halide and therefore reactable with the aminated resin polymer at amino groups thereof and without formation of water by cross linking, under heat treatment-with the aminated resin polymer molecules at the" amino groups thereof, adding abrasive grain' to the resultant plastic substantially non-tacky massand mixing the abrasive particles throughout the mass, shaping the resultant abrasive mix, and heat-treating the shaped mix to react said halide agent with the resin to produce a hardened abrasive article free from detrimental swelling.

15. The steps in the method of avoiding swelling due to'water of reaction formed during the making an abrasive article utilizing phenolic resin as a bond ingredient, which comprise wetting abrasive grain with a liquid halide plasticiz-' ing and resin-hardening resin-solvent agent, admixing with the wetted abrasive grain an aminated potentially reactive phenolic resin, said halide hardening and plasticizing agent being incapable of material cross-linking with the resin at ordinary temperatures and being capable oi cross-linking therewith, under heat treatment and without production of water of reaction. at the amino groups of the aminated resin polymer molecules, shaping the resultant abrasive mix, and heat-treating to react said halide agent with the resin to produce a hardened abrasive article free from detrimental swelling.

16. The steps in the method of making an abrasive article which comprise making up a mix comprising aminated potentially reactive phenolic resin, abrasive grain, and a polyhalide resinhardening resin-solvent agent incapable oi! material cross-linking with the resin polymer molecules at ordinary temperatures but capable of cross-linking therewith under heat treatment at the amino groups thereof to form ajhardened halogenated resin, shaping the mix, and reacting the aminated phenolic resin and the polyhalide agent by heat-treating the shaped mix to effect hardening.

17. A method of avoiding substantial formation of water in the making of a phenolic-resinbonded abrasive-article comprising the steps of mixing together aminated potentially reactive phenolic resin, abrasive particles, and a resinhardening resin-solvent agent therefor that is incapable of reacting with the resin to Iorm water in that it is capable of cross-linking with the aminated resin polymer molecules only at the amino groups thereof, shaping the mix, and

- heat treating the mix to harden the bond to secure the abrasive particles and thereby form a substantially unswelled phenolic-resin-bonded abrasive article.

18. A method of avoiding substantial formation of water in the making 01! a phenolic-realmbonded abrasive article comprising the steps of mixing together potentially reactive phenolic resin, abrasive particles, an aminating agent for the resin for reaction therewith to provide amino groups in the polymer molecules of the resin. and

. which the cross-linking halide resin-hardening a resin-hardening resin-solvent agent that is incapable of reacting with the resultant aminated phenolic resin to form water in that it is capable oi. cross-linking therewith only at the amino groups in the polymer molecules of the aminated resin, shaping the mix, and heat treating the mix to harden the bond to secure the abrasive particles and thereby form a substantially unswelled phenoiic-resin-bonded abrasive article.

19. An abrasive article according to claim 2 in which the halide resin-hardening resin-solvent agent is tri-glycol dichloride.

20. An abrasive article according to claim 2 in which the halide resin-hardening resin-solvent agent is di-2chlorethy1 phthalate.

21. An abrasive articleaccording to claim 2 in which the halide resin-hardening resin-solvent agent is dichlor diethyl ether. i

22. An abrasive article according to claim 7 in which the cross-linking halide esin-hardening resin-solvent agent is tri-glycol dichloride.

23. An abrasive article according to claim 7 in which the cross-linking halide resin-hardenin resin-solvent agent is di-2chlorethyl phthalate.

24. An abrasive article according to claim '7 in resin-solvent agent is dichlor diethyl ether.

25. The method of making an abrasive article according to claim 8 in which the halide crosslinking resin-hardening resin-solvent agent is tri-glycol dichloride.

26. The method of making an abrasive article according to claim 8 in which the halide cross--* linking resin-hardening resin-solvent agent is di-' 2chlorethyl phthalate. I

27. The method 01! making an abrasive article according to claim 8 in which the halide crosslinking resin-hardening resin-solvent agent is an chlor diethyl ether.

. so. The method of making an abrasive article according to claim 18 in which the resin-hardening resin-solvent agent is dichlor diethyl ether.

31. The method of making an abrasive article accordingto claim 15 in which the liquid halide plasticizing and resin-hardening resin-solvent agent is tri-glycol dichloride.

' LORING (208:8, Ja. 

